Field of the Invention
The invention is directed to a control circuit and more particularly, to a control circuit of a switch device.
Description of Related Art
An inverter is a power conversion device, which is commonly used to convert DC input power into AC output power by means of switching a power semiconductor element. In a typical photovoltaic grid-connected system, a relay and an electromagnetic interference (EMI) filter is disposed between an inverter and an electrical grid. The relay may separate the inverter from the electrical grid to prevent the inverter from being damaged due to the electrical grid recharging an inrush current to the inverter.
Although the relay can effectively separate the inverter from the electrical grid, the relay needs to be turned on by using a larger-size current. In the current technique, a fixed large current is provided to turn on the relay, but the relay after being turned on actually can be maintained in the on state by using a small current to, which causes unnecessary power consumption.